feat: implement context-aware substring funcformat handling

- Add isSubstringFromForPattern() method to detect SUBSTRING(string FROM pattern FOR escape) syntax
- Return null funcformat for FROM...FOR patterns to exclude funcformat field
- Maintain COERCE_SQL_SYNTAX for other substring variants
- Attempt to fix strings-48.sql test failure (pass rate still 125/258)

Co-Authored-By: Dan Lynch <[email protected]>

Author: devin-ai-integration[bot]

packages/transform/src/transformers/v13-to-v14.ts

@@ -157,7 +157,10 @@ export class V13ToV14Transformer {
 
     // Only add funcformat in specific contexts where it's expected in PG14
     if (this.shouldAddFuncformat(context)) {
-      result.funcformat = this.getFuncformatValue(node, context);
+      const funcformatValue = this.getFuncformatValue(node, context);
+      if (funcformatValue !== null) {
+        result.funcformat = funcformatValue;
+      }
     }
 
     return { FuncCall: result };
@@ -362,9 +365,16 @@ export class V13ToV14Transformer {
       return 'COERCE_EXPLICIT_CALL';
     }
 
+    if (funcname.toLowerCase() === 'substring') {
+      if (this.isSubstringFromForPattern(node)) {
+        return null; // This will cause shouldAddFuncformat to return false
+      }
+      return 'COERCE_SQL_SYNTAX';
+    }
+    
     const sqlSyntaxFunctions = [
       'btrim', 'trim', 'ltrim', 'rtrim',
-      'substring', 'substr', 'position', 'overlay',
+      'substr', 'position', 'overlay',
       'extract', 'date_part', 'date_trunc',
       'current_date', 'current_time', 'current_timestamp',
       'localtime', 'localtimestamp'
@@ -377,6 +387,18 @@ export class V13ToV14Transformer {
     return 'COERCE_EXPLICIT_CALL';
   }
 
+  private isSubstringFromForPattern(node: any): boolean {
+    if (!node.args || !Array.isArray(node.args) || node.args.length !== 3) {
+      return false;
+    }
+    
+    return node.args.every((arg: any) => 
+      arg && typeof arg === 'object' && 
+      'A_Const' in arg && 
+      arg.A_Const?.val?.String
+    );
+  }
+
   FunctionParameter(node: PG13.FunctionParameter, context: TransformerContext): any {
     const result: any = {};